Tuner for lighthouse tube cavity resonators



July 29, 1952 L SCHULTZ EAL 2,605,421 TUNER FOR LIGHTHOUSE TUBE CAVITYRESONATORS l ad@ Filed Sept. 17, 1945 n WW.,

,fs FIGJ l/Zl l' l l /9 /7 I l i y ,/'SA l H ./-u 5` 13A l 5 l 6" I g 6l '3` I MI Il I7 I3 n 4 ,1| |11 l l5 f INVENTORS HOWARD l.. SCHULTZHAROLD G. COOPER ATTORNEY Patented July 29, 1952 UNITED STATES PATENTOFFICE TUNER FOR LIGHTHOUSE TUBE CAVITY RESONATORS Navy ApplicationSeptember 17, 1945, Serial No. 616,922

9 Claims. (Cl. Z50- 36) This invention relates to apparatus forgenerating electrical oscillations of very high frequency and moreparticularly to arrangements for tuning resonator apparatus adapted foroperation with triode vacuum tubes having closely spaced plane elementsand constructed in a manner such as to bring the grid connection outsidethe vacuum tube to a ring shaped terminal surface, that is, tubes of atype commonly referred to as lighthouse tubes.

For the production of stable oscillations in the very high frequenciesutilizing triode vacuum ytubes of this type there has come into useresonator apparatus comprising three coaxial conductors, namely, anouter resonator cylinder connected effectively to the cathode, an innerresonator cylinder connected effectively to the anode and anintermediate resonator cylinder connected to the grid. The outer and theinner cylinders electrically define a closed space and the intermediatecylinder, partially enclosing the inner cylinder in the neighborhood ofthe anode connection. acts as a partition in such space.

The manner of operation of such resonator and an improved method oftuning the same by axial movement of the irmer of these three cylindersis found in our patent application Serial No. 493,778, filed July 7,1943, entitled Tuning of Electrical Resonators. and now U. S. Patent No.2,561,727. This application is a continuation in part of saidapplication. As there described, tuning eiect is produced by axialmovement of the inner cylinder relative to the other two cylinders andthe triode tube, direct mechanical sliding contact being maintainedmeanwhile between the cylinder and a relatively small cylindrical anodeterminal on the tube. Such direct sliding contact between the anodeterminal or stud and contact fingers on the sliding cylinder imposesmechanical stresses upon the anode stud and its seal with the glass ofthe tube, which may lead to damage to the tube. Also the travel of saidinner resonator cylinder is restricted within a range not larger thanthe length of the anode stud, which is a limitation of the tuning effectto va narrower range than might be desirable.

Accordingly itis one object of this invention to provide an electricalconnection between the inner of the three resonator cylinders and thelighthouse tube anode stud so as to permit relative axial movement ofthe inner cylinder with respect to the stud without having directmechanical contact therebetween, thereby to avoid imposing unduestresses on the anode stud due to said movement while neverthelessmaintaining electrical connection.

It is another object to provide a fixed auxiliary cylindrical conductorfitted over and mechanically and electrically connected to said anodestud with which the sliding inner resonator cylinder may make mechanicaland electrical contact thereby making the desired electrical connectionindirectly with the said anode stud.

It is another object to provide in effect by such auxiliary cylindricalconductor a much longer anode stud length so that the distance of axialtravel of said inner conductor resonator may be increased and therebythe range of frequency tuning effect increased substantially.

Other objects, features and advantages will appear in the followingdetailed description together with the drawings illustrative of theprinciples of the invention.

Fig. l is a sectional view of the type of tuning device fully andparticularly described in our earlier patent application above referredto.

Fig. 2 is a sectional view showing the preferred embodiment of ourpresent improvement in the method of making the anode connection.

Referring now to Fig. l, there is shown a conventional lighthouse tube Ihaving its radio frequency cathode (not shown) connected through itsmetallic shell 2 near its base 3 for radio frequencies, its grid (notshown) connected to a metallic ring II and its anode (not shown)connected to a metallic cylindrical stud 5 and disk 6.

The resonator structure comprises an outer tubular member 1 adapted tobe connected to the base shell 2 (and hence electrically connected tothe cathode), an inner cylindrical member 9 adapted to be connectedslidably to the anode stud 5, and a cylinder or sleeve II of a diameterintermediate between the outer diameter of the cylinder 9 and the innerdiameter of the tubular member 1, usually less than the mean of thosetwo diameters and adapted to be mounted upon the grid terminal ring 4and to be held in place thereon by one or more screws I3 and I3A.

As more fully discussed in our earlier application, cited above, thefrequency of oscillation is believed to be mainly determined by thelength of sleeve II. Furthermore, it has been observed that because ofan intense magnetic eld near the base of cylinder I I this region isappropriate for magnetic coupling to an outside circuit and hence thecoupling loop I5 and a coaxial line having inner conductor I1 and outerconductor I9 are provided as shown in Fig. l. The type of couplinghowever is not critical.

The upper end of the resonator space 2| is effectively closed off bymeans of a cup-shaped structure 2,3 mounted on the sleeve -9 which isadapted to furnish a radio frequency short circuit between the cylinder1 and the cylinder 9. An actual mechanical short circuit is undesirableboth because it is desired to adjust the position of the cylinder 9 andbecause the two are at different direct current potential levels. Theyare supported and insulated from each other by the end structure 25.

The tuning effect which is relatively wide in range results from theprovision of an adjustable sliding anode connection between the lowerend of cylinder 9 and the anode stud 5. When the cylinder 9 is slidaxially on the anode stud 5 a very strong effect on the resonantfrequency develops. This is believed to result from the conguration ofthe elds produced by the presence of the annular gap or channel betweenthe anode disk 6 and the bottom end of the sliding cylinder 9. The usualsize anode stud is about a quarter of an inch long. With greater lengthf anode stud a greater tuning range could be obtained because the amountof axial travel of cylinder 9 could be increased.

At the upper end cylinder 9 is threaded and engaged in a bushing 21which is suitably embedded in the insulating terminating structure 25.The axial position of the cylinder 9 may be adjusted by turning a knob29 mounted on the end of cylinder 9 and made preferably of insulatingmaterial.

The knob 29 is provided with an axial opening 3| to permit introductionof an electrical conductor (not shown) for connection to the anode ofthe tube. A knurled nut 33 of insulating material is provided forlocking the cylinder 9 at any desired position of adjustment. Lockingpairs of nuts 34 and 35 and 36 and 31 provide for limiting the extent ofaxial movement of cylinder 9 so that it cannot be moved downwardly sofar as to exert undue pressure on the anode stud and disk 6 andstructure of the vacuum tube 1, and so that it cannot be retractedupward far enough to lose contact with the anode stud 5. As will be seenthis latter pair of nuts 36, 31 may be omitted in the later versionclaimed by this application since the range of retraction is greatlyincreased.

Our earlier application cited above made general reference to thepossibility of diiferent types of sliding anode connection for examplesuch as a sliding joint provided between two portions of the cylinder 9in the neighborhood of the stud 5. Referring now to Fig. 2 there isshown a particular embodiment of the present invention which permitsgreater range of tuning and also a reduction of mechanical stress on theanode stud 5 and structure of the tube I, through utilization of adifferent construction of the inner resonant cylinder 9A and its mannerof connection with the anode stud 5.

All the rest of the structure shown in Fig. 2 is identical with that ofthe earlier form shown in Fig. 1 including vacuum tube l, outerresonator cylinder 1, intermediate resonator cylinder ll and theirvarious supporting and adjusting means previously described (some notbeing shown in Fig. 2). Likewise the shorting member 23 is unchanged.

In this improvement shown in Fig. 2 the anode resonator cylinder 9Awhich is caused to slide axially to produce tuning effect does not slidedirectly along the surface of the anode stud 5 but upon an auxiliarycylindrical member 5A which is in stationary contact with the anode stud5. This auxiliary member 5A may be solid or hollow and is suitablysupported so as to remain in stationary contact with the anode stud 5.The anode resonator cylinder 9A is supported and attached in anadjustable manner as in the pre- 5 vious invention so that its axialposition is adjustable.

Because the member 5A is in stationary contact with it, the stress uponthe anode stud 5 caused by movement of cylinder 9A is greatly 10reduced. Also the travel of member 9A along member 5A is not restrictedby the size of the anode stud 5 as was the case in the previousinvention, hence the tuning range is increased.

What is claimed is: 1. An oscillator for high frequencies including avacuum tube having an anode, cathode, grid, and external connectorstherefor, a tunable circuit structure comprising a plurality ofsubstantially coaxial conductive cylinders of differing diameters, afirst of said cylinders being electrically connected to the cathode ofsaid tube, an auxiliary cylinder being in stationary connection with theanode connector of said tube providing an extension of the anodeconnector, a second of said coaxial conductive cylinders being inaxially slidable connection with the outer surface of said auxiliarycylinder, a third of said coaxial conductive cylinders intermediate saidrst and second coaxial conductive cylinders being connected near one endto said grid connector and having at its other end a substantially opencircuited termination, and means connected to said second cylinder fortuning said structure by causing axial motion of said second cylinderwhich is slidably connected with the auxiliary cylinder and thusindirectly connected to the anode connector, whereby the configurationof the oscillating eld in the neighborhood of said slidable connectionmay be varied and the frequency of oscillations varied in accordancewith 5he axial position of said second cylinder.

""WZ. An oscillator for high frequencies including ,a" vacuum tubehaving an anode, a cathode, a grid and external connectors therefor, atunable circuit structure which comprises a rst conductive cylinderconnected to the anode connector of said tube, a second conductivecylinder substantially coaxial with said rst named cylinder andconnected therewith by means of an axially slidable joint, a thirdconductive cylinder substantially coaxial with and partially enclosingsaid second conductive cylinder and connected to the cathode connectorof said tube, a fourth conductive cylinder substantially coaxial withthe aforesaid second and third cylinders and located therebetween, saidfourthcylinder being connected near one end to the grid connector ofsaid tube and extending a relatively short distance beyond said gridconnector, the other end of said cylinder extending over but spaced froma portion of said second conductive cylinder and extending to asubstantially open circuited termination, the said cylinders connectedto said cathode connector and to said rst cylinder respectively beingeffectively joined for the frequency of operation by a conductingstructure located between said cylinders at a point a substantialdistance beyond the said Qpen-circuited end of said fourth cylinder, andmeans operative on said second cylinder for axial adjustment of theposition of said second cylinder relative to the cathode connectedcylinder and relative also to said rst cylinder, whereby said axiallyslidable connection may be operated and the configuration of anoscillating electrical eld in the neighborhood of said anode changedthereby varying the frequency of operation.

3. A lighthouse tube high frequency oscillator, a tunable circuitstructure comprising four substantially coaxial conductive cylinders,the first of which is rmly axially juxtaposed in contact with the anodeconnection of said lighthouse tube, the second of which is in axiallyslidable contact with the outside of said first cylinder, the third ofsaid cylinders being connected to the cathode connection of said tube,the fourth of said cylinders being positioned intermediate of the secondand third named cylinders and connected to the grid connection of saidtube, said second and third cylinders being eiectively short circuitedat a point remote from the end of the third named cylinder, and meansconnected to said second cylinder for adjusting the relative axialposition of said second named cylinder with respect to the remainder ofsaid cylinders and said tube, said means being adapted to provide avariable annular space in the immediate neighborhood of the anodeconnection and thereby to enable frequency tuning of the said circuitstructure.

4. A high frequency oscillator comprising, in combination, a vacuum tubeof the lighthouse type having an external disk and stud connector forits anode and external ring connectors for its cathode and grid, firstand second coaxial hollow conducting cylinder respectively connected tosaid cathode and grid connectors, a third cylinder having a, diameterslightly larger than the diameter of said stud axially juxtaposed incontact with said stud, a fourth conducting cylinder having a diameterintermediate said first and third cylinders axially slidably connectedat one end to said third cylinder and mounted coaxially therewith, saidone end of said fourth cylinder and the disk portion of said anodeconnector deiining an annular channel of variable axial dlmension in theimmediate neighborhood of said anode connector, and means connected tosaid fourth cylinder for adjusting said fourth cylinder axially relativeto said third cylinder thereby controlling said variable axialdimension.

5. An oscillator for high frequencies comprising, in combination, avacuum tube of the lighthouse type having an external disk and studconnector for its anode and external ring connectors for its cathode andgrid, a conductive cylindrical extension having a diameter substantiallyequal to the diameter of the stud portion -of said anode connectoraxially juxtaposed in contact with said anode connector, iirst andsecond coaxial cylindrical conductors connected respectively to thecathode and grid connectors of said tube, said second conductor beingintermediate said extension and said first conductor and connected nearone end to said grid connector and having at its other end asubstantially open-circuited termination, and a third conductingcylinder intermediate said extension and said second conductor andslidably connected at one end to said extension, said one end of saidthird cylinder being enclosed by said second cylinder and defining withthe disk portion of said anode connector an annular channel surroundingsaid extension, and means connected to said third cylinder for movingsaid third cylinder axially relative to said extension therebycontrolling the axial dimension of said annular channel.

6. An electronic oscillator comprising an electron tube having an anode,cathode and grid,

electrodes, and external connectors therefor, iirst, second and thirdcoaxial cylindrical conductors, said first and second conductors forminga resonant circuit between the anode and grid electrodes, said secondand third conductors forming a resonant circuit between the grid andcathode electrodes, said first and third conductors forming a resonantcircuit between said anode and cathode electrodes, an auxiliarycylindrical conductor positioned in stationary connection with saidanode connector and providing an axial extension therefor, said iirstcylindrical conductor being in axially slidableconnection with the outersurface of said auxiliary conductor, and means connected to said rstcylinder for tuning said oscillator by causing movement of said firstcylinder relative to said auxiliary conductor whereby the configurationof the oscillating field in the neighborhood of said slidable connectionmay be varied.

7. An oscillator comprising, in combination, an electron tube having ananode, cathode, grid, and external connectors therefor, and a tunablecircuit structure. said structure comprising iirst, second, third andfourth coaxial conductive cylinders of differing diameters. said firstcylinder being electrically co ,y ected to the cathode connector of saidtubeaid second cylinder being in stationary connection with the anodeconnector f said tube and forming an extension therefonsaid thirdcylinder being in axially slidable con ection with the outer surface ofsaid second cylinder, said fourth cylinder being intermediate said rstand third cylinders and connected near one end to the grid connector ofsaid tube and having at its other end a substantially open-circuitedtermination, and means connected to said third cylinder'for causingaxial motion thereof relative to said second cylinder whereby theconfiguration of the oscillating field in the neighborhood of saidslidable connection may be varied and the frequency of the oscillatorvaried in accordance with the axial position of said third cylinder.

8. Apparatus for tuning an oscillator of the type which includes alighthouse type electron tube having an external disk and stud connectorfor its anode and iirst and second coaxial conductive cylindersrespectivelyconnected to the cathode and grid connectors of said tube,said apparatus comprising a conductive cylindrical extension for saidstud having a diameter slightly larger than the diameter of said studaxially juxtaposed in contact therewith, and a third conducting cylinderintermediate said extension and said second cylinder slidably connectedat one end to said extension, said one end of said third cylinder andsaid disk deiining an annular channel of variable axial `dimensionsurrounding said extension.

9. Apparatus for tuning an oscillator of the type which includes alighthouse type electron tube having an external disk and studconnectorl for its anode, and rst and second concentric conductivecylinders respectively connected to the cathode and grid connectors ofsaid tube. sald apparatus comprising. an auxiliary cylindrical conductorpositioned coaxially with said iirst and second cylinders andelectrically connected at one end to said anode stud and forming anaxial extension therefor, a third conductive cylinder having a diameterintermediate said cylindrical conductor and said second cylinder mountedconcentrically with said cylindrical conductor and electricallyconnected at one end to said cylindrical conductor. said third cylinderbeing in axially slidable connection with REFERENCES CITED the outersurface of said auxiliary conductor and The following references are ofrecord n the being formed at said one end to define in coopme of thispatent: eration with said disk an annular channel sur'- rounding saidconductor in the region of said 5 UNITED STATES PATENTS anode connectorof said tube, and means secured Number Name Date to said third cylinderfor adjusting the axial po- 2,404,113 Wagner July 16, 1946 sition ofsaid third cylinder relative to said con- 2,408,355 Turner Sept. 24,1946 ductor whereby the axial dimension of said 2,408,927 GurewitschOct. 8, 1946 channel may be varied. 10 2,429,811 Guan-era Oct. 28, 1947HOWARD L. scHULTz. OTHER REFERENCES HAROLD G. COOPER. Electronics, vol.19, No. 2, February 1946, pp.

